Damping device



June 14, 1960 G. P, PATRIQUIN DAMPING DEVICE 2 Sheets-Sheet l Filed April 19, 1957 INVENTOR 19 V GEORGE P. PATRIQUIN June 14, 1960 G. P. PATRIQUIN DAMPING DEVICE Z Sheets-Sheei 2 Filed April 19, 1957 INVENTOR GEORGE P. PATRIQUIN MMM-7 QORNEY United States Patent O DAMPING DEVICE George P. Patrquin, Gardner, Mass assigner to Independent Lock Company, Fitchburg, Mass., a corporation of Massachusetts Wed Apr. 19, 1957, Sex'. No. 653,925

4 Claims. (Cl. 16-66) .This invention relates to a momentum arresting device, -and more particularly to a device for arresting the momentum of a closing door for prevention of slamming. Still more particularly, this invention relates to a pneumatic device which utilizes the principle of controlled air -escape from a cylinder `to cushion or dampen a spring biased door against slamming under the closing biasing pressure of the spring.

Known to me are momentum arresting devices of the controlled air escape type which employ escape or bleed ports at the high pressure end. Such known constructions ,may generally be divided into two categories, to wit, those employing a iixed size bleed port, and those having la variable bleed port. While the latter constructions allowed greater ilexibility by providing some control over the rate at which the door would close, both said known constructions possess inherent disadvantages, in that in both there is found a bounce or recoil when the door reaches a nearly closed position. The recoil or bounce not only puts additional strain on the structure of the door and its hanging hardware, but is also frequently accompanied by an annoying sound.

Many attempts have been made on such known structures to limit door bounce, but heretofore no ne have been successful. One unsuccessful method attempted was the reduction of the size of the air exhaust port. Other unsuccessful attempts to relieve bounce have taken lthe form of auxiliary air release means, believed toprovide pressure relief at the point where bounce is usually encountered.

Accordingly, it is an object of my invention to provide a momentum arresting device, such as adoor closer, which will cause a door to progress smoothly throughout the closing cycle without exhibiting the bounce or oscillatory recoil frequently found in connection with the use of such arresting devices. A further object of my invention is to provide a pneumatic momentum arresting device of the type described in which the period of time required for the closing cycle maybe variably controlled, while still maintaining lthe no-bounce advantages as aforesaid. v I

Still a further object of my invention is to provide a door device of the pneumatic type which may be easily adjusted to maintain the no-bounce and controlled closing period advantages above mentioned, while nevertheless remaining adaptable for use o'n doors of a wide range of weights and widths, and, accordingly, the variably encountered momentums.

ln order more fully to illustrate and describe my invention, I make reference to the accompanying drawings, forming a part hereof, in which:

` Figure l is a side elevation of my device installed on a door;

Figure 2 is a diagrammatic View, partially in phantom, illustrating the bounce effect by showing the sequential positions assumed by a known prior art device during a closing cycle;

Y Figure 3 is a simplified diagram showing the bounce etect in other prior art devices by showing the sequential positions of the leading edge of the door during a closing cycle;

-Figure r4 is a magnied plan view of -my device at an open position of the door taken on the lines 4-4 of Figure l, with parts broken away to show the piston, and showing same in broken lines at the closed position of the door;

Figure 5 Vis a further magnified longitudinal section taken on the lines 5-5 of Figure 4;

Figure 6 is a .magnified plan view, with parts broken away, showing the assembly holding the door yin the open position;

Figure 7 is a magnied longitudinal section of the bleed valve assembly taken on the line 7.--7 of-Figure 5;

Figure 8 is a magnified cross-section taken on vthe line 8--8 of Fig. 5.

In order more clearly to illustrate the bounce etiect found yin prior art devices, I have illustrated in Figure 2 the relative door and cylinder positions of a known pneumatic door closer employing the expedient of an ancillary port in the form of a by-pass, believed to act as a bounce reducer, and in Figure 3 a diagram of typical leading door edge positions during the closing cycle of a prior art device, without any form of bounce reducer. (The letters A, B, C, D, E represent the cycle sequentially in alphabetic order: (A) the normal closed position; (B) the fully open position; (C) the initial damped position in closing; (D) the bounce or recoil; (E) the fully closed position.) g

In Figure 2, the door Y is shown in the full open position B, in dotted lines. In this latter `position the piston P is retracted from the full stroke position in the cylinder R which it occupies, compressing the spring S behind the piston head. When the door is in the closed position A, the spring S has expanded and the expansive force urges the door Y toward the closed position. The latter spring closing force is opposed by a pressure head which builds up in the high pressure end H of the cylinder head R, and a variable port 0 may be provided to allow the air slowly to escape. As the door Y swings lfrom the B position to the C position, its momentum gradually increases while at the same time the tension of the spring S gradually is dissipated, with the result that the air trapped in the high pressure end H is believed to be unable to escape quickly enough through the port O. As a result of this inability to escape, the increased pressure in the high end H exerts a counter force on the piston P, with the result that the door lbounces backward to the D position. It is also possible that a collapse in damping causes slamming and bouncing, notwithstanding the spring pressure. In the D position, the pressure head is believed to be reduced by reason of the slight retraction of the piston in the cylinder accompanying return of the door to the D position and the further air escape through the port O. After `bouncing to the D position, the door closes to the A position, under the recoil of the spring which has again been compressed from the position C to D.

The known device shown in Figure 2 is chosen as one which is provided with an auxiliary port V which permits air to escape only when the door is in the C position shown. The eiect of providing an auxiliary air relief at this point is believed to lessen the pressure at the point where bounce is likely to occur, and thereby to the bounce caused by back pressure. While the auxiliary port eectively reduces bounce when the door is left to close by spring tension only, it is obvious that if other forces come into play earlier to increase the pressure, the bounce will develop earlier in the closing cycle before the piston reaches the auxiliary port position. .In such a ease, the bounce-reducing properties of the auxiliary port will not be utilized. Examples of forces likely to cause early bounce arewind pressure, vvand unduly hard manual slamming. j The diagram of Figure 3 isincluded more clearly -to illustrate typical opening andY closing positions of the leading edge of a door equipped with a non-auxiliary port type of prior art device, the arcuate arrows indicating the direction of door movement from one position to the next. I ascribe the bounce-free performance of my device lto the use of a novel bleed type valve, and particularly to' the use of such valve in combination withjpneuinatic piston and cylinder assemblies similar to those exempliiied by the prior art devices previously mentionedandgdescribed. While I have illustrated and described my ,pneumatic inertia arrester in connection with a door closer, itshvould v be borne in mind that my inventionis lnot tobe restricted to use in conjunction with door closing devices, since minor structuralV variations willrender my device useful in many situations where pneumatic damping is practicable and where it is desirable thatv such damping be smooth land bounce-free.

' As applied to a door closing device, in accordance with my invention, a vcylinder 10 has a cap or cylinder head 11 threaded to or otherwise alixed at' one end of the cylinder. The said cylinder is. pivotallyjmounted on a door 12 by'providing thecap 11 Ywith a pair'of parallel spaced extending knuckles 13 which are preferably formed integrallyV with said cap 11.* The knuckles 13 are proi vided with axially aligned'bearing apertures 14 which are adapted to coincide with'A apertures^15 formed in the lugs 16 of the U-shaped bracket 17. The bracket 17, which is rigidly Vafxed tto the door 12, is thus pivotally coupled Vtothe'cylinder'cap 11 by a pintle 18 which ispassed through the apertures 14 and 15 when the bracket lugs 16 areV positioned over the cap arms A13. A piston rod 19 is slidably supported and axially guided by the piston rod bearing 20 formed through a cylinder cap 21a, which may be threadedly or otherwise aixed to the end V22a of said cylinder 10 opposed to Vsaid door supported end.

' The rod 19 has an eye 21 formed therethrough and is pivotally joined to the bracket 22 by positioning the eye 2170i the'rod519 between the opposed apertures 23-23 formedY in the extending sides 24-24 of the bracket 22, and by'V then passing a -trunnion 25 through rthe apertures -23-23 :and the eye 21. The Vbracket'22 may be an- 'chored to the door frame F by wood screws or other means.- Y Y` lAdjacent the inner end of the piston rod 19 is formed the threaded vportion 26 and the annular shoulder 2 7. -A support washer 28 is positioned over the rod 19'and seated against the shoulder 27. A cup-shapedV exible seal orpiston ring cup 29 is positioned against the support washer 28, and a resilient cup spreaderV 30, having outwardly extending spring lingers 31, is nested within the said seal or cup 29V and is there maintained by the compressive force of the nut 32 acting on the f retaining washer33, the fingers31 tendingto maintain the cup 29 in spread condition. The thus supported seal or cup 29 forms a-.slidable but airtight `fit against the inner walls of the cylinder 10, and for convenience the assembly will be hereinafter referred to as the piston 34.

VA11 adequate coil spring 35 is normallylightly biased between the support washer28V of the piston 34 anda shoulderI 36 formed `on the Vinner end of the cap 21a and serves to maintain the piston 34 at a position near positionrof theV installation on theY door. and Vframe.-

The Vcapll (see Figure 7)` has a centrallyl formed'pas.-

sembly39 -is comprised ofa plug 40 having at the inner end 41 Yan air passage 42 'runningY through and connected the/cap 11, Yas will beunderstood-to bethe closed door 4 to a Wider passage `43 by a frusto-cenical seat'44. The remainder of the inner portion of the plug passage 43 is threaded, as at 45. A ball 46 is urged into the frustoconical seat 44 forming a closure therefor under the biasing pressure of spring 47. The spring 47 is seated at the end opposite to the ball end against the head of the screwthreaded bleed screw 48.A A fcentralair bleed passage 49 runs through the bleed screw- 48, for purposes which willappear. e -f. .Y Y

The bleedscrew 48 Vis threadedWithinv the plug .portion 45, with the spring 50Ainterposed between thehead 51 of the screw 48 andthe plug `4Q at the cap surface, thereby to provide fn'ctional resistance preventing accidental turning of the screw 48... r j f j r At a point near the end of the piston stroke, the cylinder 10 is provided with a raised, elongated by-pass passage 51a, which is of a length to span the piston assembly 34. It should be noted that when the by-pass passage 51a straddles the seal 29 Vofthe piston-34 `(see Figure 5), an air passage is provided'whicli circumvents the sealing inuence of the piston34.V 'Y

The door to which my assembly is appliedmybe temporarily held in the open or partially open position'by sliding the oversize washer 52 against thestud 53 projecting from the cap 21a, with the door in the position sought to be maintained.

TheY closing biasing influence ofthe spring 35 is rendered inoperative to lclose the door by reasonof thefrictional caiiting and wedging of the washer 52 against 'the'.rod 19, causedby the pressure ofthe stud 53 against the washer 52. Release of the door is accomplished by further opening .the door and thereafter 'sliding the washer? away from the pistonend of the rod 19.1 i' "i Upon openingthe door 12, thepis'tonl34is withdrawn to a position'inthe cylinder 10 near-the vcapy end 21d, bythe outward movementof 'saidcylinder 10 caused by opening thedoor 12. This relative movement 4of `the piston 34 and the cylinder 10 causes the spring 35 to be compressed between the support Ywasher 28 and the cap shoulder 36. When released in the fully or partlyV opened position, the spring 35 urges the piston 34`back toward the cap 11, thereby moving the door 12 to the closed position. On the return stroke of the piston'35 .toward the cap 11, the trapped in the cylinder head of the cylinder 10 between the'seal 29 Yof the piston34 and the cap 11, is compressed, thus 'tending `to`oppose the biasing closing action of the spring 35 and thereby damp- -ing the momentum Vof the swinging` door. The pressure of the trapped air increases until it' becomes suicient to unseat the valve or closure forming' ball 46 from the vseat 44 against the closing biasing inu'ence of the spring 47, thereby enabling the trapped air` gradually to be evacuated through the passages 37, 42 and 49," thus kallowing the door 1 2 slowly to close. Inward o r outward threading of the bolt 48 increasesor'decreases thetension'o'n the spring 47,'thus varying the pressure required t'o unseat the ball 46, and thereby rendering adjustable the' pressureV on the ball while making this valve variably respon sive tothe speed of the door and variably determining sure'hasV become sujiciently reduced toallowthefdoor smoothly to complete the closing cycle, and latchnhe doorinthe closed position..` y i 21E; 'i n `It should be-understood Vthat .While'theinclusiollof the vby-passSla contributes toa desirableY operation 'of the illustrated embodiment, I do not wish to have my .invention restricted tovuse therewith? vsitiethe ideiiticalg'structure, omitting only the by-pass, has been found by me in a measure satisfactorily to eliminate bounce.

An inertia-arresting device in accordance with my invention will be found to reduce the wear and tear on doors, door frames, hanging hardware and like door parts, which result from the shocks which accompany the use of known door closers which are subject to the bounce or like oscillatory recoil. While prior art devices using a form of by-pass have a tendency to slam to the closed position after the by-pass point of the cylinder is reached by the piston, the embodiment of my invention which includes the by-pass is free from any such final bouncing tendency, when adjusted to release the ball under the accumulated compressed air in the cylinder head.

it should also be observed that while I have described what l believe to be the inherent mode of operation of my assembly, it is not intended to be limited by the explanation, and that my invention is to be limited only by the scope of the appended claims.

While my invention has its primary utility as an inertiaarresting device for doors, it is possible to utilize my invention in conjunction with many pneumatic damping applications, and particularly in many long thrust pneumatic devices where bounce-free operation is desirable. My invention, accordingly, is not to be restricted in scope to use with a door closer, but rather, the scope of the claims should be construed broadly to apply to the pneumatic damping iield.

Having thus described my invention and illustrated its use, what I claim as new and desire to secure by Letters Patent, is:

l. A door closer or like momentum dampener comprising a pneumatic cylinder having a sealed end, a piston axially slidable in said cylinder toward and away from said sealed end, a spring mounted in said cylinder to bias said piston toward said sealed end and a valve mounted in said sealed end, said valve forming the sole means of air passage through said sealed end and including a compression spring normally holding said valve closed during the initial portion of the closing stroke of said piston whereby the pressure of the air trapped in said cylinder increases until it opens said valve and permits evacuation of the trapped air, resulting in the slow closing of the door.

2. A door closer in accordance with claim 1 wherein said valve may be variably biased by rotation of a bleed screw for venting the trapped air when said valve is opened, said bleed screw being threaded through said sealed end and bearing against said compression spring.

3. A door closer in accordance with claim 2 wherein said valve comprises a frusto-conical seat and a ball normally biased into said frusto-conical seat.

4. A door closer in accordance with claim 1 wherein said cylinder includes an auxiliary pressure release bypass passage formed integral with said cylinder at a 1ocation near the end of the closing piston stroke.

References Cited in the file of this patent UNITED STATES PATENTS 

